REPORT ON THE ASTEROIDEA. 297 
1. Nymphaster symbolicus, n. sp. (Pl. L. figs. 1 and 2; Pl. LIII. figs. 7 and 8). 
Rays five. R=85 mm.; r=26mm. R>325 7. The minor radius is thus in the 
proportion of about 30 per cent. 
General form flat and thin. Disk large and pentagonal. Rays elongate, narrow, and 
tapering continuously to a slender extremity ; width midway between the centre of the 
disk and the extremity, 8°25 mm.; width at the commencement of the outer fourth, 
4mm. Interbrachial arcs wide and openly rounded. 
The marginal plates are broad and massive, the outer part forming a vertical lateral 
wall, the abactinal and lateral areas of the plate being at right angles to one another, with 
the junction abrupt and subangular. The intermediate paxillar area is on a level with the 
supero-marginal plates, and the section of the ray is almost rectangular in outline, its 
horizontal diameter being twice the vertical near the base of the ray, but decreasing in 
proportion as it proceeds outward. The supero-marginal plates are thirty-three in number 
from the median interradial line to the extremity. Their length is little more than their 
height, and their breadth is nearly twice their height. On the outer part of the ray the 
length is greater than the breadth, the height remaining the least dimension. The surface 
of the plates is covered with a uniform, small, semiglobular, miliary granulation. The 
granules do not touch one another, but closely cover the whole plate, and at the lateral 
margins form a lineal series which helps to define the sutures between adjacent plates. The 
median surface of the plate is faintly convex. Hach of the plates, except at the end of the ray, 
may bear one or two long entrenched pedicellariz on the abactinal surface, and frequently 
(at least in large specimens) a rather smaller one also at the angular junction of the abactinal 
and lateral surfaces, but which may not, however, proceed very far along the ray. These 
pedicellariz have the appearance superficially of a straight cut or slit about 1:25 mm. in 
length, intersected midway by a very small but wider cross cut; the jaws of the pedi- 
cellarize have somewhat the form of the letter T, with its vertical line greatly prolonged ; 
and when retracted, fit exactly in the excavations above described. The pedicellariz 
have no definite posture on the plates. The odd terminal plate is comparatively large in 
relation to the neighbouring marginal plates; it is elongately shield-shaped, with the 
angular extremity directed inward, and the outer portion of the plate rounded sub- 
cylindrically and contracting slightly and gradually towards the extremity, which is 
obtuse. The infero-marginal plates correspond to the superior series, the rounding 
towards the actinal area being rather more decided. They are covered with a precisely 
similar small granulation, and each usually bears one of the entrenched pedicellarize on 
the actinal surface. The breadth of the infero-marginal plates diminishes rapidly after 
passing the base of the ray, and thence to the extremity the length becomes the largest 
dimension. 
The armature of the adambulacral plates consists of a furrow series of ten delicate, 
rather elongate spinelets, flattened laterally to a uniform thickness but tapering towards 
(zooL. CHALL, EXP.—PART L1.—1888.) 38 
